Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of a display screen or portion thereof with transitional graphical user interface showing my new design in a first appearance state;

FIG. 2 is a front view of the design of FIG. 1 in a second appearance state;

FIG. 3 is a front view of the design of FIG. 1 in a first appearance state, shown with additional unclaimed elements to further illustrate environmental structure; and,

FIG. 4 is a front view of the design of FIG. 1 in a second appearance state, shown with additional unclaimed elements to further illustrate environmental structure.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-2 and FIGS. 3-4. The process or period in which one image transitions to another image forms no part of the claimed design.

The broken lines showing a display screen or portion thereof, text, and other elements are for the purpose of illustrating environmental structure and form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 